1. Field of the Invention
The present invention relates to a pumping system, especially relates to the control of a pumping system that pressurizes fluid and jets the fluid from a nozzle selected out of a plurality of nozzles.
2. Description of the Related Art
There is a pumping system in which a plurality of nozzles are connected to a pump via selecting arrangement and which jets fluid discharged by the pump from the nozzle selected by the selecting arrangement. Such a pumping system is used for a cleaning device disclosed in JP-A No. H8-90365 for example. In the cleaning device disclosed in JP-A No. H8-90365, a plurality of nozzles are arranged on the upside of a turret which is selecting arrangement. Fluid discharged by the pump is jetted from one nozzle selected by the selecting arrangement.
The discharge pressure of a positive-displacement pump is determined by the rotational speed (the speed of rotation per unit time) of the positive-displacement pump, the contour of a jet of the nozzle and the jet hole diameter of the nozzle. When selected nozzles are switched, fluid is jetted with pressure according to the newly selected nozzle according to a curve showing relation between the discharge pressure and the discharge flow rate of the pump.
When cleaning, chipping, deburring or other work is performed using a pumping system, the discharge flow rate or the discharge pressure of a pump and acquired effect closely relate. Accordingly, when a plurality of works are performed using the plurality of nozzles, it is desirable that optimum discharge pressure or optimum discharge flow rate is selected every work.
An object of the present invention is first to keep the discharge pressure or the discharge flow rate of the fluid in a pumping system that jets from a nozzle selected out of a plurality of nozzles at a value set every selected nozzle.
A nozzle is gradually abraded by jetted fluid, a jet hole diameter is extended, and the contour of the jet is deteriorated. As detergency and deburring capacity are influenced by discharge pressure, the contour of the jet and discharge flow rate, the abraded nozzle is replaced. A conventional type pumping system is configured so that a pressure-relief valve is provided to a discharge opening of a pump and discharge pressure is kept a value constant by the pressure-relief valve. When the discharge pressure is deteriorated, the relief pressure of the pressure-relief valve is regulated and when predetermined discharge pressure cannot be held by the closure of the pressure-relief valve, a nozzle is replaced. However, the time of replacement cannot be estimated.
The object of the present invention is second to verify a situation of abrasion of a nozzle and inform the proper time to replace the nozzle.